With regard to a valve operating device for lifting a valve of an internal combustion engine provided in a vehicle or the like, JP2004-204822A, published by the Japan Patent Office in 2004, discloses a valve operating device that lifts a valve by causing a rocker cam to contact a rocker arm such that a stem end of a valve stem contacting the rocker arm is pushed.
The valve stem is biased in a direction for closing the valve by a valve spring. When the rocker cam pushes the rocker arm, the valve stem is pushed down while causing the valve spring to contract. As the valve stem is pushed down, the valve opens.
When the pressure applied to the rocker arm by the rocker cam is released, the valve is pushed up by a spring force of the valve spring, thereby closing the valve. The valve spring keeps the rocker arm pressed against the rocker cam via the valve stem so that the rocker arm does not separate from the rocker cam as the rocker cam rocks.